by Robert Bowling, Assistant Professor and Extension Specialist –Integrated Pest Management (IPM)
Sugarcane aphid on sorghum in Hildalgo County was detected on March 21, 2017 by Danielle Sekula-Ortiz. Sugarcane aphid colonies were small and the field had not reached an economic population but there are several important considerations with this detection.
- Winged aphids were found in some of the colonies. This means the aphid is mobile and strong southerly winds will carry the aphid into other areas of the Rio Grande Valley and eventually to the Upper Gulf Coast and point north. This detection comes three to four weeks earlier than the first detection in 2016.
- Dry and unseasonably warm conditions prompted early establishment of row crops in the Valley. Residual activity of insecticide seed treatments is generally 30 up to 50 days after planting. Sorghum seeded in late-January will no longer be protected by an insecticide seed treatment. Regardless of insecticide seed treatment and planting date, now is a good time to initiate early detection of sugarcane aphid in your sorghum. Pay close attention to field borders, more especially if volunteer sorghum remnant sorghum, or Johnsongrass borders these fields. I was in Willacy county the same day the aphid was detected in Hildago county. I did not find sugarcane aphid on sorghum I scouted but I did find them on remnant sorghum in a ditch and on several patches of Johnsongrass.
- Scout all sorghum! Many farmers will plant sugarcane aphid tolerant sorghum this year. It is important to remember that no sorghum hybrid is immune to sugarcane aphid. All fields should be treated as though they were susceptible to the aphid to avoid possible surprises.
- Transform did receive approval on sorghum for use against sugarcane aphid in 2017.The label is the same as it was in 2016. If you need to review the label see the following link: https://www.texasagriculture.gov/Portals/0/Publications/PEST/Sect18/16TX02%20Transform%20WG%20Sec%2018%20Directions.pdf . Sivanto is available and the 4 oz/a rate has offered exceptional performance against this aphid in south Texas.
Early detection of sugarcane aphid in the Valley does not necessarily mean this will be an aphid year on sorghum. There are many environmental factors that could suppress the aphid. If we get into a warm and dry-cycle, then things may get a little interesting. However, the best way to handle any crop pest is routine scouting, utilizing thresholds (average of 50 to 125 aphids per leaf for Texas with exception to the High Plains), spraying once thresholds are reached (highly suggested to do so within 3 days after the population reaches the threshold), and use enough carrier (minimum of 10/gallons per acre by ground or 5 gallons per acre by air) to penetrate the canopy and maximize coverage on lower leaves. Always read and follow the manufacturer’s labeled directions. Deviating from the label will nullify any implied warranty offered by the manufacturer.
On a side note, yellow sugarcane aphid was not detected in the fields scouted on March 21. Hopefully this aphid will remain quiet in 2017. But, as always, scout for the presence of any pest that may cause an economic loss in production. We will continue to scout the aphid and provide updates.